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Weigh, weigh the best – time and time again!

Posted on 3rd September 2007 by

We are delighted to report that one of the ‘Spiroflow’ Flexible Spiral Conveyors with which our name is synonymous is performing ‘brilliantly’ for boiled sweet manufacturer Joseph Dobson & Sons Ltd. In the application at Dobson’s, the conveyor is operating as a reliable, accurate and highly repeatable volumetric feeder. It is delivering sugar from a sack tip hopper to a steam pan some 3 metres away. It is in this steam pan, a pressure vessel mounted on load cells, that the base ingredients of sugar, glucose and water are weighed, mixed and pre-heated before being transferred to traditional open pans where the resultant mass is boiled to perfection.

Turning the clock back some 7 years, the management team at Joseph Dobson embarked upon a programme of measures to improve and automate selected elements of their operation. The areas for improvement were chosen on the premise that they must not compromise the heart of their boiled sweet making process. This is the process that has served the company well since 1850 and which, today, still delivers the quality and tradition reflected in the growing demand for their products. All of the selected measures were associated with three key improvement objectives: hygiene, health and safety and labour saving.

Prior to the installation of the ‘Spiroflow’ Flexible Screw Conveyor, sugar was manually weighed in to food grade buckets, lifted shoulder high and tipped in to the steam pan – an operation needing improvements to satisfy all three key objectives.

Initially the conveyor was approximately two and a half times the length it is now and included three bends. This is not usually recommended, one continuous curve is the norm! Nevertheless, the conveyor operated very satisfactorily this way for 6 years before requiring a new spiral. At the same time as replacing the spiral it was decided that the ‘Spiroflow’ Conveyor should be shortened, so as to eliminate the unwanted bends, and also we were asked to provide a new sack tip hopper for use within the boiling room itself. The resultant conveyor and sack tip hopper give incredibly reliable feed rates over a given time. The steam pan requires a preset quantity of sugar. As the sugar, glucose and water are all added to the steam pan simultaneously, the load cells can only check that the total weight is within tolerance. To ensure that the ratio of oil flavourings, essential oils and colour elements do not exceed their legal limits, the sugar content must never be less than the preset quantity but, too much more has an adverse effect on quality. For traceability and record purposes the ‘Spiroflow’ Conveyor is recorded daily and the results show that over a running time of 9.4 minutes it consistently delivers the required set weight. As Managing Director, Stephen Walshaw comments, “We are ecstatic about the accuracy”.
Joseph Dobson & Son Ltd’s historical factory frontage. The ‘Spiroflow’ Flexible Screw Conveyor, in the boiling room.
Joseph Dobson & Son Ltd’s historical factory frontage.

The ‘Spiroflow’ Flexible Screw Conveyor, in the boiling room.

The 20 employees at Joseph Dobson & Sons Ltd are currently producing in excess of 2 million boiled sweets a week. They make at least 42 ‘boilings’ during an 8 hour shift. Accordingly, the accuracy and reliability of the ‘Spiroflow’ Flexible Screw Conveyor is crucial to the achievement of output. Each boiling is poured onto a temperature controlled confectionery table. Skilled operatives then mix and continuously fold the boiling to homogenously blend in the flavourings, essences, medicinal and colour elements which are added a this point to produce that range of ‘Yorkshire Mixtures’, ‘Humbugs’, Pear Drops’, ‘Voice Tablets’ and ‘Butter Mintoes’ for which Joseph Dobson are renowned throughout the world. The boiling is then shaped and die-cut into individual sweets ready for packaging.

As Cathy Podevyn, Sales our Marketing Director comments, “This application at Joseph Dobson is a clear demonstration of the operational improvements that can be made by utilising a ‘Spiroflow’ Flexible Screw Conveyor – it is usually the lowest cost means of transferring powders and granular material in a hygienic dust-free manner.”

In conclusion, Stephen Walshaw says, “Spiroflow are brilliant to deal with. They give us all the support we need quickly and efficiently”.